A peer-to-peer (or P2P) computer network relies primarily on the computing power and bandwidth of the participants or peers in the network rather than concentrating it in a relatively low number of servers. P2P networks are typically used for connecting nodes via largely ad hoc connections. P2P networks are overlay networks formed by a set of cooperating peers connected over a packet network, such as an Internet Protocol (IP) based network or the Internet. P2P networks are useful for many purposes. Sharing content files (see file sharing) containing audio, video, data or anything in digital format is very common, and realtime data, such as telephony traffic, is also passed using P2P technology.
A pure peer-to-peer network does not have the notion of clients or servers, but equal peer nodes that simultaneously function as both “clients” and “servers” to the other nodes on the network. This model of network arrangement differs from the client-server model where communication is usually to and from a central server. A typical example for a non peer-to-peer file transfer is an FTP server where the client and server programs are quite distinct, and the clients initiate the download/uploads and the servers react to and satisfy these requests.
Most P2P networks require minimal configuration of nodes for them to participate in the network. As a general node, a new node wishing to join needs to know the identity of any node on the P2P network in order to join it. To facilitate that, P2P networks require some form of bootstrapping to allow a peer, when it first comes online, to discover the identities of a few nodes within the P2P network. From there, the newly initialized peer can insert itself in the right place and no longer utilize the bootstrap nodes. Typically, a centralized client-server mechanism is utilized to allow a newly initialized peer to discover and obtain information from a bootstrap node. A centralized bootstrapping mechanism, however, does present certain administrative challenges as it requires some entity to support and maintain the bootstrapping mechanism.